JP4254582B2 - Valve lift amount adjusting mechanism and adjusting method for internal combustion engine - Google Patents

Description

  The present invention relates to a valve lift adjustment mechanism for an internal combustion engine that swings a rocker arm with the rotation of a camshaft and swings a swing cam provided on the camshaft to swing the valve with the swinging motion of the rocker arm. And an adjustment method.

  Conventionally, for example, the following Patent Documents 1 and 2 describe a valve operating mechanism that variably controls a valve lift amount according to a change in an engine operating state in order to improve engine performance.

This is because the swing cam opens and closes the intake valve by the rotational force transmitted from the drive cam, which is an eccentric rotating cam provided on the camshaft, via the rocker arm, link member, etc., and the control is arranged parallel to the camshaft. The control cam on the outer circumference of the shaft is rotationally controlled to change the rocking fulcrum of the rocker arm, thereby making the valve lift variable according to the operating state.
JP 2002-221014 A JP-A-11-107725

  By the way, in the above-described conventional valve operating mechanism, the valve lift amount is determined by the dimensional accuracy of a plurality of link parts. Therefore, the valve lift amount varies among the cylinders due to the dimensional accuracy. And the adjustment work to make this valve lift amount appropriate is to measure the valve lift amount with the valve mechanism assembled, and then disassemble and then replace the link member to be adjusted with a different length. It is necessary, and the workability is deteriorated.

  Therefore, an object of the present invention is to make it possible to easily adjust the valve lift amount.

  The present invention swings the rocker arm with respect to the swing support shaft as the camshaft rotates, swings the swing cam provided on the camshaft as the rocker arm swings, and opens and closes the valve. In the valve lift adjustment mechanism of the internal combustion engine, the rocker arm is supported so as to be swingable with respect to the swing support shaft via an eccentric bush, and both of the two are mutually connected between the eccentric bush and the rocker arm. The most important feature is that it includes a coupling portion that can be switched between a swingable state relative to the swing support shaft and a relatively rotatable state.

  According to the present invention, the rocker arm is swingably supported with respect to the swing support shaft via the eccentric bush, and the eccentric bush can be rotated relative to the rocker arm when adjusting the valve lift amount. It is only necessary to switch to the state and rotate it by a predetermined angle with respect to the rocker arm. Thereby, the valve lift amount can be adjusted without disassembling the valve operating mechanism after assembling, and the valve lift amount can be easily adjusted. be able to.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view of a valve operating mechanism equipped with a valve lift amount adjusting mechanism for an internal combustion engine according to an embodiment of the present invention at the time of adjusting the valve lift amount, and FIG. is there. The valve mechanism here is applied to the intake side, and includes two intake valves 1 per cylinder, and a variable valve that makes the valve lift amount of each intake valve 1 variable according to the engine operating state. It has a mechanism.

  In other words, this variable valve mechanism is slidably provided on the cylinder head 2 via a valve guide, and a pair of intake valves 1 as a valve urged in the closing direction by the spring force of the valve spring, and the cylinder head 2, a drive shaft 3 as a hollow camshaft rotatably supported by the upper bearing 4, a single drive cam 5 that is an eccentric rotary cam fixed to the drive shaft 3, and an outer periphery of the drive shaft 3. A swing cam 7 that is movably supported and slidably contacts the upper surface 6a of the valve lifter 6 disposed at the upper end of each intake valve 1, and a drive cam 5 and a swing cam 7 that are linked to drive. A transmission mechanism 8 that transmits the rotational force of the cam 5 as a swinging force of the swing cam 7 and a control mechanism 9 that controls the operating position of the transmission mechanism 8 are provided.

The drive shaft 3 is arranged along the longitudinal direction of the engine, and the rotational force is transmitted from the crankshaft of the engine via a driven sprocket (not shown) provided at one end or a timing chain wound around the driven sprocket. This rotation direction is set in the counterclockwise direction (arrow direction) in FIG.
The drive cam 5 is formed in a substantially annular shape by a wear-resistant material, and as shown in FIG. 2, the drive cam 5 is formed so as to penetrate through the drive shaft insertion hole 5a in the internal axis direction. Offset by a predetermined amount β in the direction. Further, the drive cam 5 is fixed to the drive shaft 3 and rotates counterclockwise in FIG. 2 as the drive shaft 3 rotates.
The valve lifter 6 is formed in a cylindrical shape with a lid, and is slidably held in the holding hole 2a of the cylinder head 2, and an upper surface 6a of a rocking cam 7 on which a cam body 7a (described later) comes into sliding contact is formed in a flat shape. is doing.
The swing cam 7 includes a pair of substantially raindrop-shaped cam bodies 7 a integrally provided at both ends of a substantially cylindrical base end portion 10, and a support hole formed in the inner axial direction of the base end portion 10. The entire drive shaft 3 is swingably supported, and a pin hole 11a is formed through a cam nose portion 11 provided on one end side of one of the two swing cams 7. Further, the cam surface formed on the lower surface of each cam body 7 a abuts on a predetermined position on the upper surface 6 a of each valve lifter 6 according to the swing position of the swing cam 7 to change the valve lift characteristics.
The transmission mechanism 8 includes a rocker arm 13 disposed above the drive shaft 3, a link arm 14 connecting the one end 13 a of the rocker arm 13 and the drive cam 5, the other end 13 b of the rocker arm 13, and the swing cam 7. And a link member 15 for connecting the two.

  The rocker arm 13 is rotatably supported by a control cam 23 serving as an eccentric cam, with a cylindrical base portion 13c at the center integrated with an eccentric bush 22 described later.

  The rocker arm 13 has a support hole 13d in a cylindrical base portion 13c at the center, and the eccentric bush 22 is fixedly coupled to the support hole 13d (FIG. 1 is released from this coupled state). The shaft is integrally supported with the eccentric bush 22 so as to be swingable and rotatable with respect to a control cam 23 of a control shaft 32 as a swing support shaft described later.

  3 and 4 are exploded perspective views of the rocker arm 13 and the eccentric bush 22. FIG. 3 corresponds to a view seen from the direction of arrow B in FIG. 1, and FIG. 4 is a view seen from the direction of arrow C in FIG. It corresponds to.

  A pin 16 is provided at one end portion 13a of the rocker arm 13 projecting from one end outer side of the cylindrical base portion 13c, and the pin 16 is rotatably inserted into a through hole 14d formed at the end portion of the link arm 14. Link. On the other hand, a through hole 13e is formed in the other end portion 13b projecting from the outer end of the other end of the cylindrical base portion 13c, and the connecting pin 17 is inserted into the through hole 13e and the through hole 15a formed at the end portion of the link member 15. The rocker arm 13 and the link member 15 are rotatably connected.

  The link arm 14 shown in FIG. 1 and FIG. 2 is a base end portion 14a that is a relatively large-diameter annular end portion, and the other end portion that projects from a predetermined position on the outer peripheral surface of the base end portion 14a. A projecting end 14b, and at the central position of the base end portion 14a, a fitting hole 14c is formed to be rotatably fitted to the outer peripheral surface of the drive cam 5. On the projecting end 14b, the pin 16 is provided. The above-described pin hole 14d that is rotatably inserted is formed through. The axis 16 a of the pin 16 is a pivot point of the one end 13 a of the rocker arm 13.

  Further, the link member 15 has both end portions 15b and 15c rotatably connected to the other end portion 13b of the rocker arm 13 and the cam nose portion 11 of one cam body 7a by the connecting pin 17 and the connecting pin 30, respectively. ing.

Further, the shaft centers 17 d and 30 a of the connecting pins 17 and 30 serve as pivot points of the both end portions 15 b and 15 c of the link member 15, the other end portion 13 b of the rocker arm 13, and the cam nose portion 11 of the swing cam 7. .
As shown in FIG. 1, the control mechanism 9 includes a control shaft 32 that extends in the longitudinal direction of the engine in parallel with the drive shaft 3 at a position above the drive shaft 3 and is rotatably supported by the bearing 4 described above. The control cam 23 fixed to the outer periphery of the control shaft 32 and serving as the rocking fulcrum of the rocker arm 13; a DC motor for controlling the rotation of the control shaft 32 via a ball screw mechanism or a gear mechanism (not shown); And a controller for controlling driving of the motor.

  The axis of the control cam 23 is offset by a predetermined amount with respect to the axis of the control shaft 32, thereby variably controlling the valve lift according to the change in the engine operating state.

  Further, as shown in FIG. 2, the position of the axial center P2 of the outer circumferential circle of the eccentric bush 22 inserted into the support hole 13d of the rocker arm 13 is the axial center of the control cam 23 (ie, the eccentric bush). The center of the inner circumferential circle of 22) is offset from P1 by α.

  As shown in FIGS. 3 and 4, the eccentric bush 22 includes a cylindrical portion 39 that is rotatably inserted with respect to the control cam 23 of the control shaft 32 by an inner circumferential circle and rocks integrally with the rocker arm 13. It is movable and is movable in the axial direction with respect to the control cam 23 and the rocker arm 13. The cylindrical portion 39 includes a thick portion 39a in a part in the circumferential direction, and an outer peripheral gear 39b is provided over the entire circumference on one end side of the outer peripheral portion.

  On the other hand, as shown in FIG. 4, an inner peripheral gear 13 f is provided on one end of the inner surface of the support hole 13 d of the rocker arm 13, and the cylindrical portion 39 of the eccentric bush 22 is supported by the rocker arm 13. By inserting it into the hole 13d, the outer peripheral gear 39b and the inner peripheral gear 13f are engaged with each other and are connected to each other. In other words, the outer peripheral gear 39b and the inner peripheral gear 13f constitute a coupling portion that allows the eccentric bush 22 and the rocker arm 13 to be switched between a state in which the eccentric bush 22 and the rocker arm 13 can swing integrally with each other and a state in which relative rotation is possible.

  Further, a rotational drive gear 41 having a diameter larger than that of the cylindrical portion 39 is provided at a position further adjacent to the end side than the outer peripheral gear 39b of the cylindrical portion 39. The rotational drive gear portion 41 includes: It meshes with a pinion 43 connected to a drive shaft 36a of a valve lift adjustment motor 36 serving as a rotation drive unit. That is, the eccentric bush 22 rotates with respect to the control cam 23 by driving the valve lift adjustment motor 36.

  The rotational drive gear 41 is provided approximately semicircularly with respect to the cylindrical portion 39, and a gap 47 for inserting the fixing bolt 45 is provided between the cylindrical portion 39 and the outer peripheral surface. On the other hand, on the rocker arm 13 side, a boss portion 13g is integrally provided at the other end portion 13b, and a screw hole 13h into which the fixing bolt 45 is screwed is formed in the boss portion 13g. Then, by inserting the fixing bolt 45 into the gap 47 and screwing it into the screw hole 13h, the eccentric bush 22 and the rocker arm 13 are integrated to restrict relative movement in the axial direction.

  The controller in the control mechanism 9 detects the current engine operating state by calculation based on detection signals from various sensors such as a crank angle sensor, an air flow meter, a water temperature sensor, and a throttle opening sensor, A control signal is output to the DC motor based on a detection signal from a potentiometer that detects the rotational position of the control shaft 32.

According to the valve mechanism described above, at the time of engine low speed and low load, the DC motor is rotated by a control signal from the controller, and the control shaft 32 is rotated clockwise in FIG. 2 through the gear mechanism and the ball screw mechanism. To do. For this reason, the eccentric bush 22 moves to the rotation angle position in which the axis P2 is lower left in FIG. 2 with respect to the axis P1 of the control cam 23 . That is, the thick portion 39 a is moved from the drive shaft 3 side to the axis 16a side. For this reason, the entire rocker arm 13 rotates counterclockwise from the state shown in FIG. 2, and the cam body 7 a is forcibly pulled up by the cam nose 11 side via the link member 15 and the entire cam body 7 a is counteracted. Rotate clockwise.

  Therefore, when the drive cam 5 rotates and pushes up the one end portion 13a of the rocker arm 13 via the link arm 14 during the opening / closing operation of the intake valve 1 in this state, the lift amount of the rocker cam 13 via the link member 15 is increased. 7 and the valve lifter 6, but the lift amount is sufficiently small.

  Here, when the valve lift amount in the valve operating mechanism varies between the cylinders, the valve lift amount is adjusted according to the present invention. That is, after the fixing bolt 45 shown in FIG. 4 is removed, the eccentric bush 22 is moved in the axial direction with respect to the control cam 23 and the rocker arm 13, and the outer peripheral gear 39b of the eccentric bush 22 and the inner peripheral gear 13f of the rocker arm 13 are moved. Is released, and the combined state of these two is released.

  The amount of movement of the eccentric bush 22 in the axial direction is only required to disengage the outer peripheral gear 39b from the inner peripheral gear 13f. In this disengaged state, the cylindrical portion 39 supports the outer peripheral surface of the control cam 23 and the rocker arm 13. It can rotate between the holes 13d and can move in the axial direction.

  In this state, the valve lift adjustment motor 36 is driven to rotate the eccentric bush 22 by a predetermined amount. FIG. 5A is a schematic diagram showing, as an example, a state before adjustment, and FIG. 5B is a schematic view showing each component as a link after the adjustment. In addition, the adjustment work here has shown the case where it adjusted to the direction where the valve lift amount becomes small in FIG.5 (a) from FIG.5 (b). The link position indicated by a two-dot chain line in FIG. 5B corresponds to the link position in FIG.

  That is, by rotating the eccentric bush 22 in the clockwise direction in the drawing from the state before adjustment in FIG. 5A, the rocker arm 13 rotates counterclockwise from the state in FIG. As a result, each cam body 7a is forced to be pulled up via the link member 15 and the entire cam body 7a rotates counterclockwise. As a result, the cam body 7a shifts to the adjusted state shown in FIG.

  In the state after adjustment in FIG. 5B, the link length P connecting the center 23b of the control cam 23 and the axis 17d of the connecting pin 17 is thicker than in the state before adjustment in FIG. The length 39a is shortened by the distance from the shaft center 17d, and the shaft center 17d is positioned above. Along with this, the shaft center 30a of the connecting pin 30 in the cam nose portion 11 also moves slightly upward and to the right.

  On the other hand, when adjusting in the direction of increasing the lift amount, the eccentric bush 22 may be rotated counterclockwise in the figure from the state of FIG. As a result, the link member 15 is lowered, and the swing cam 7 can be rotated in the clockwise direction in FIG. 2 to adjust the lift amount to be increased.

  According to the above-described embodiment, when adjusting the valve lift amount, the eccentric bush 22 provided between the rocker arm 13 and the control cam 23 may be rotated with the rocker arm 13 removed. Since it is not necessary to disassemble the mechanism after assembling, there are less restrictions on the work space, the adjustment work of the lift amount becomes extremely easy, and the production cost can be reduced.

  As a means for fixing the eccentric bush 22 and the rocker arm 13, a bush retaining preventing member 49 as shown in FIG. 6 can be used instead of the fixing bolt 45 shown in FIG.

  The bush retaining member 49 is provided with a cover portion 49a that covers a part of the outer peripheral surface of the rocker arm 13, and axial ends of the cover portion 49a. The cylindrical portion 39 of the eccentric bush 22 is connected to the support hole 13d of the rocker arm 13. In this state, two retaining arms 49 b that cover one end of the eccentric bush 22 and two retaining arms 49 c that cover the other end of the rocker arm 13 are provided.

  In addition, when covering the above-described bush retaining member 49 from above the rocker arm 13, it is from the side opposite to the rotational drive gear portion 41 provided on the eccentric bush 22.

  According to the present invention, the coupling portion includes an outer peripheral gear provided on the outer peripheral surface of the eccentric bush, and an inner peripheral gear that is meshable with the outer peripheral gear and provided on the inner peripheral surface of the rocker arm. The bush is movable in the axial direction with respect to the swing support shaft, and the outer peripheral gear and the inner peripheral gear are displaced between the meshing state and the non-meshing state, so that the coupling state between the eccentric bush and the rocker arm is ensured. Therefore, the meshing state and the non-meshing state can be easily displaced.

  In addition, since the eccentric bush that rotates the eccentric bush with the outer peripheral gear and the inner peripheral gear disengaged with respect to the swing support shaft is provided, the eccentric bush can be easily rotated. Can do.

  Furthermore, since the rotation drive unit is provided with a pinion and the eccentric bush is provided with a gear portion that meshes with the pinion, power transmission from the rotation drive unit to the eccentric bush can be reliably performed.

  The swing support shaft is provided with an eccentric cam that is eccentric with respect to the shaft center of the swing support shaft, and that rotates with the rotation of the swing support shaft, thereby making the valve lift variable. Since the eccentric bush is rotatably provided on the outer periphery of the cam, the valve lift amount can be adjusted without disassembling the valve lift amount adjustment work in the variable valve mechanism after the valve mechanism is assembled. It is possible to easily adjust the lift amount.

  The eccentric bush includes a cylindrical portion that is positioned between the rocker arm and the eccentric cam in a state where the outer peripheral gear and the inner peripheral gear are engaged and non-engaged. The cylindrical portion can slide and rotate between the rocker arm and the eccentric cam.

It is a perspective view at the time of valve lift amount adjustment of the valve operating mechanism provided with the valve lift amount adjustment mechanism of the internal combustion engine concerning one embodiment of the present invention. FIG. 2 is a side sectional view taken along arrow A in FIG. 1. FIG. 2 is an exploded perspective view of a rocker arm and an eccentric bush viewed from the direction of arrow B in FIG. 1. FIG. 2 is an exploded perspective view of a rocker arm and an eccentric bush viewed from the direction of arrow C in FIG. 1. FIG. 5A is a schematic view showing a state before adjustment, FIG. 5B is a schematic view showing the state after adjustment, and each component is a link. It is a perspective view of the bushing prevention member used as a fixing means of a rocker arm and an eccentric bush.

Explanation of symbols

1 Intake valve
3 Drive shaft (camshaft)
7 Oscillating cam 13 Rocker arm 13f Inner gear of rocker arm 22 Eccentric bush (joint)
23 Control cam (Eccentric cam)
32 Control shaft (swing support shaft)
36 Valve lift adjustment motor (rotary drive)
39 Cylindrical part of eccentric bush 39b Outer peripheral gear (joint part) of eccentric bush
41 Gear part for rotation drive (gear part)
43 Pinion

Claims (7)

  A valve for an internal combustion engine that swings a rocker arm with respect to a swing support shaft as the camshaft rotates and swings a swing cam provided on the camshaft as the rocker arm swings to open and close the valve. In the lift amount adjusting mechanism, the rocker arm is supported so as to be swingable with respect to the swing support shaft via an eccentric bush, and the two are integrally formed with each other between the eccentric bush and the rocker arm. A valve lift adjustment mechanism for an internal combustion engine, comprising: a coupling portion that can be switched between a swingable state relative to a swing support shaft and a relatively rotatable state.   The coupling portion includes an outer peripheral gear provided on the outer peripheral surface of the eccentric bush and an inner peripheral gear that is meshable with the outer peripheral gear and provided on the inner peripheral surface of the rocker arm. 2. The valve lift adjustment mechanism for an internal combustion engine according to claim 1, wherein the outer peripheral gear and the inner peripheral gear are displaced in a meshing state and a non-meshing state so as to be movable in an axial direction with respect to a shaft. .   3. A valve for an internal combustion engine according to claim 2, further comprising a rotation drive unit that rotates the eccentric bush with the outer peripheral gear and the inner peripheral gear disengaged with respect to the swing support shaft. Lift amount adjustment mechanism.   4. The valve lift adjustment mechanism for an internal combustion engine according to claim 3, wherein a pinion is provided in the rotation drive part, and a gear part meshing with the pinion is provided in the eccentric bush.   The swing support shaft is provided with an eccentric cam that is eccentric with respect to the shaft center of the swing support shaft, and that rotates with the rotation of the swing support shaft, thereby making the valve lift variable. The valve lift amount adjusting mechanism for an internal combustion engine according to any one of claims 1 to 4, wherein the eccentric bush is rotatably provided on an outer periphery of the cam.   The said eccentric bush is provided with the cylindrical part located between the said rocker arm and the said eccentric cam, when the said outer peripheral gear and the said inner peripheral gear are a meshing state and a non-meshing state. The valve lift adjustment mechanism of the internal combustion engine.   A valve for an internal combustion engine that swings a rocker arm with respect to a swing support shaft as the camshaft rotates and swings a swing cam provided on the camshaft as the rocker arm swings to open and close the valve. In the lift amount adjusting method, the rocker arm is swingably supported with respect to the swing support shaft via an eccentric bush, and the eccentric bush is integrated with the rocker arm via a coupling portion. The state in which the eccentric bushing and the rocker arm can rotate relative to the dynamic support shaft is changed to a state in which the eccentric bush and the rocker arm can rotate relative to each other. After rotating a predetermined angle with respect to the rocker arm, the eccentric bush and the rocker arm are united by the coupling portion. The valve lift amount adjusting method for an internal combustion engine according to symptoms.

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